A giant magnetoresistive (GMR) element that is constituted by a multi-layer film of a ferromagnetic layer and a nonmagnetic layer, and a tunnel magnetoresistive (TMR) element using an insulating layer (a tunnel barrier layer, a barrier layer) as a nonmagnetic layer are known. Typically, the TMR element has higher element resistance in comparison to the GMR element, but a magnetoresistance (MR) ratio of the TMR element is greater than an MR ratio of the GMR element. According to this, the TMR element has attracted attention as an element for a magnetic sensor, a high-frequency component, a magnetic head, and a nonvolatile magnetoresistive random access memory (MRAM).
In the MRAM, data is read and written by using characteristics in which when magnetization directions of two ferromagnetic layers with an insulating layer interposed therebetween vary, element resistance of the TMR element varies. As a writing type of the MRAM, a type in which writing (magnetization reversal) is performed by using a magnetic field formed by a current, and a type in which writing (magnetization reversal) is performed by using spin transfer torque (STT) that occurs when a current is allowed to flow in a lamination direction of a magnetoresistance effect element are known. The magnetization reversal of the TMR element which uses STT is efficient from the viewpoint of energy efficiency, but a reversal current density for magnetization reversal is high. It is preferable that the reversal current density is low from the viewpoint of a long operational lifespan of the TMR element. This preference is also true of the GMR element.
Accordingly, in recent years, as means for reducing a reversal current with a mechanism different from the STT, a magnetization reversal type using a pure spin current generated by a spin Hall effect has attracted attention (for example, Non Patent Literature 1). The pure spin current, which is generated by the spin Hall effect, causes spin-orbit torque (SOT), and causes magnetization reversal by the SOT. The pure spin current is generated when the same numbers of upward spin electrons and the same number of downward spin electrons flow in directions opposite to each other, and flows of charges are canceled. According to this, a current that flows to a magnetoresistance effect element is zero, and thus realization of a magnetoresistance effect element having a small reversal current density is expected.
According to Non Patent Literature 2, it is reported that a reversal current density by the SOT type is approximately the same as a reversal current density by the STT type. However, the reversal current density that is reported in the current SOT type is not sufficient to realize high integration and low energy consumption, and thus there is room for improvement.
In addition, examples of a material that is used in the spin-orbit torque wiring (wiring that causes SOT and generates a pure spin current) of the magnetoresistance effect element of the SOT type include a heavy metal material including Ta that is used in Non Patent Literature 2. The heavy metal material has high electric resistivity. Therefore, when the heavy metal material is used as a thin film or a thin wire, there is a problem that power consumption is high.